Most democratic governments would fall immediately if they were found to have shot down a civilian airliner and then tried to cover it up. Iran, however, is not a democracy, and despite Saturday's humiliating admission that it did, in fact, shoot down Ukraine Airlines flight PS752, there is little chance of Supreme Leader Ali Khamenei or his acolytes stepping down. Instead, the strategy appears to be blame low-level officials for the tragedy. According to President Hassan Rouhani, all those responsible for the "terrible catastrophe" will be identified and prosecuted, be it the military commanders who fired the fatal shot on Wednesday or the hapless media spokesmen who peddled denials for three days afterwards. Everyone, in other words, except Mr Khamenei - who, by virtue of his very title of Supreme Leader, is where the buck should surely stop. Still, having to perform such a rare act of public contrition may well inhibit Iran from further retaliation over America's a...